Two-stage blown air system and method for foamed articles

Abstract

Two-stage blown air systems for foamed materials inject a first gas at a first pressure into the interior of a parison and then inject a second gas at a second pressure into the interior of the parison in forming a container.

1 . A method, comprising: 
 firstly injecting a first gas at a first pressure into a parison interior of a parison; and    secondly injecting a second gas at a second pressure into the parison interior to form a container,    wherein the parison comprises a foamed material.    
     
     
         2 . The method of  claim 1 , wherein the second pressure is lesser than or equal to the first pressure.  
     
     
         3 . The method of  claim 1 , further comprising drawing a vacuum at a mold wall to pull the parison onto the mold wall.  
     
     
         4 . The method of  claim 1 , further comprising heating a mold wall surrounding the parison.  
     
     
         5 . The method of  claim 1 , wherein the foamed material comprises polymer capsules that enclose a gas.  
     
     
         6 . The method of  claim 1 , wherein the first gas is injected at the first pressure for a first predetermined period of time.  
     
     
         7 . The method of  claim 6 , wherein the first predetermined period of time is in a range of from about 10% to about 20% of the total blow cycle time.  
     
     
         8 . The method of  claim 1 , wherein the second gas is injected at the second pressure for a second predetermined period of time.  
     
     
         9 . The method of  claim 1 , wherein the first pressure is in a range of from about 15 psig to about 40 psig and the second pressure is less than about 20 psig.  
     
     
         10 . The method of  claim 9 , wherein the first pressure is about 20 psig and the second pressure is about 10 psig.  
     
     
         11 . The method of  claim 1 , wherein the first gas and the second gas are air.  
     
     
         12 . A method, comprising forming a plurality of containers, each container formed in a cycle comprising the method of  claim 6 , 
 wherein the second gas is injected at the second pressure for a second predetermined period of time.    
     
     
         13 . The method of  claim 12 , wherein at least one of the first pressure and the second pressure varies between at least two cycles.  
     
     
         14 . The method of  claim 12 , wherein at least one of the first predetermined period of time and the second predetermined period of time varies between at least two cycles.  
     
     
         15 . A two-stage blown air system, comprising: 
 an injection nozzle;    a first gas source of a first gas at a first pressure;    a second gas source of a second gas at a second pressure;    a multi-way valve, comprising a common port, a first supply port, and a second supply port;    the common port fluidly coupled to the injection nozzle;    the first supply port fluidly coupled to the first gas source;    the second supply port fluidly coupled to the second gas source; and    a mold having a mold wall.    
     
     
         16 . The system of  claim 15 , wherein the second pressure is lesser than or equal to the first pressure.  
     
     
         17 . The system of  claim 15 , wherein the second gas source comprises a second gas pressure regulator, the second gas pressure regulator is fluidly coupled to the multi-way valve, and the second gas pressure regulator and the first gas source are for fluidly coupling to a main gas source.  
     
     
         18 . The system of  claim 15 , wherein the first gas source comprises a first gas pressure regulator, the second gas source comprises a second gas pressure regulator, the first gas pressure regulator is fluidly coupled to the multi-way valve, the second gas pressure regulator is fluidly coupled to the multi-way valve, and the first gas pressure regulator and the second gas pressure regulator are for fluidly coupling to a main gas source.  
     
     
         19 . The system of  claim 15 , further comprising a vacuum source, 
 wherein the mold wall comprises mold wall openings and the mold wall openings are coupled to the vacuum source.    
     
     
         20 . The system of  claim 15 , further comprising a heat source, 
 wherein the mold wall is coupled to the heat source.    
     
     
         21 . The system of  claim 15 , further comprising a timer coupled to the multi-way valve, for triggering the multi-way valve to inject the first gas at the first pressure through the injection nozzle for a first predetermined period of time and for triggering the multi-way valve to inject the second gas at the second pressure through the injection nozzle for a second predetermined period of time.  
     
     
         22 . The system of  claim 21 , the timer comprising a first predetermined period of time set adjust and a second predetermined period of time set adjust.  
     
     
         23 . The system of  claim 18 , further comprising: 
 a computer;    the computer coupled to the multi-way valve, for triggering the multi-way valve to inject the first gas at the first pressure through the injection nozzle for a first predetermined period of time and for triggering the multi-way valve to inject the second gas at the second pressure through the injection nozzle for a second predetermined period of time;    the computer coupled to the first gas pressure regulator for adjusting the first gas pressure regulator to the first pressure; and    the computer coupled to the second gas pressure regulator for adjusting the second gas pressure regulator to the second pressure,    wherein a user can adjust the computer to set at least one of the first predetermined period of time, the first pressure, the second predetermined period of time, and the second pressure.